One known type of information storage device is a disk drive device that uses magnetic media to store data and a movable read/write head that is positioned over the media to selectively read from or write to the disk.
FIGS. 1-2 illustrate a conventional disk drive device 200 and show a magnetic disk 101 mounted on a spindle motor 102 for spinning the disk 101. A voice coil motor arm 104 carries a HGA 100 that includes a micro-actuator 105 with a slider 103 incorporating a read/write head. A voice-coil motor (VCM) is provided for controlling the motion of the motor arm 104 and, in turn, controlling the slider 103 to move from track to track across the surface of the disk 101, thereby enabling the read/write head to read data from or write data to the disk 101. In operation, a lift force is generated by the aerodynamic interaction between the slider 103, incorporating the read/write transducer, and the spinning magnetic disk 101. The lift force is opposed by equal and opposite spring forces applied by a suspension of the HGA 100 such that a predetermined flying height above the surface of the spinning disk 101 is maintained over a full radial stroke of the motor arm 104.
FIGS. 3a-3b illustrate the HGA 100 of the conventional disk drive device of FIGS. 1-2. As illustrated, the HGA 100 includes a suspension 106 comprising a base plate 108, a load beam 110, a flexure 109 and a hinge 107, and all these components are assembled together. The flexure 109 has a suspension tongue 179 formed thereon to load the piezoelectric (PZT) micro-actuator 105 and the slider 103. In addition, inner suspension traces 111 and outer suspension traces 112 are formed on the flexure 109. The suspension traces 111 and 112 have their one ends electrically coupled to the PZT micro-actuator 105 and the slider 103 respectively, while the other ends thereof are electrically connected with a plurality of electric connection pads 113, which is electrically connected with an external control system (not shown) in turn. By the external control system, operation of the PZT micro-actuator 105 and the slider 103 is properly controlled.
Referring to FIG. 3c, a conventional PZT micro-actuator 105 used in the HGA 100 described above includes a metal frame 123, which has a top support 121 for supporting the slider 103 (referring to FIG. 3a), a bottom support 122 for mounting the whole micro-actuator 105 to the suspension 106 (referring to FIG. 3a), and two side arms 120 that interconnect the two supports 121 and 122. The side arms 120 each have a PZT element 116 attached thereto. Each PZT element 116 has two electrical connection pads 185 formed at one end thereof. The slider 103 is supported on the top support 121 and disposed between the two side arms 120.
As shown in FIGS. 3b-3c, the PZT micro-actuator 105 is physically coupled to the suspension tongue 179 by the bottom support 122. A plurality of electrical connection balls 117 is provided to couple the PZT micro-actuator 105 to the inner suspension traces 111. Namely, an electrical connection pad 186, which is electrically connected to the inner suspension traces 111, is provided on the suspension tongue 179 at a position adjacent the electrical connection pads 185 of each PZT element 116. These pads 185 and 186 are electrically interconnected together by the electrical connection balls 117. In addition, there are four metal balls 115 for coupling the slider 103 to the outer suspension traces 112 for electrical connection of the read/write transducers thereof to the external control system. When power is supplied through the inner suspension traces 111, the PZT elements 116 expand or contract to cause the two side arms 120 to bend in a common lateral direction. The bending causes a shear deformation of the frame 123, which causes movement of the top support 121. This causes movement of the slider 103 connected thereto, thereby making the slider 103 move on the track of the disk in order to fine tune the position of the read/write head.
It is desired that the PZT elements have a big deformation so that the slider can get a stroke value (displacement) as big as possible during operation, thereby improving data reading/writing performance thereof. However, in conventional technology described above, since an electrical connection between the PZT element 116 and the inner suspension traces 111 occurs at one end of the PZT element 116 where the electrical connection pads 185 are formed, the connection results in fixation of this end of the PZT element 116 relative to the inner suspension traces 111 (more concretely, the suspension), i.e., the end becomes undeformable due to restraint of the suspension, thus negatively deteriorating deformability of the whole PZT element 116, and accordingly, making the stroke value of the slider reduced greatly.
Thus, there is a need for an improved micro-actuator that does not suffer from the above-mentioned drawbacks.